Highest temperature in Tokyo on July 4?

Platform comparison

Market context

The underlying real-world event is the highest temperature recorded at Tokyo Haneda Airport on 4 July 2026, a date that historically sits within Tokyo’s peak summer heat window. Current crowd-implied probability for a “YES” outcome is 0%, yet Polymarket prices the 27°C range at 57% and 26°C at 26%, suggesting the market expects a high of 26–27°C rather than extreme heat. This contrasts with July 3’s market, which assigned 100% probability to 26°C, and aligns with historical averages: Tokyo’s July mean is 28.4°C, with highs often exceeding 30°C for consecutive days, though recent years show variability due to humidity and cloud cover [3][2].

Traders should monitor Wunderground’s first data point for 4 July, as resolution hinges on its publication, and watch for any sudden shifts in local weather forecasts from AccuWeather, which currently predicts daily highs of 76–91°F (24–33°C) for Haneda in July 2026 [5]. The on-chain mechanics—USDC settlement on Polygon via conditional tokens—mean liquidity can move rapidly if new forecast data emerges, especially given Japan’s record-breaking July average temperature of 28.7°C in 2024, driven by 77.6% humidity [8]. No major weather announcements are scheduled, but the dependency on real-time data publication creates a clear catalyst window for price discovery before the 2026-07-04T12:00:00Z settlement deadline.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Tokyo on July 4? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.